伊犁地区冰雹气候特征及环境场分析

Analysis on the Hail Climatic Characteristics and Environmental Fields in Ili Area

利用线性回归分析、Mann-Kendall检验,统计分析了1961-2018年伊犁地区10个国家站冰雹日数的气候特征,同时利用2000-2018年伊宁站探空资料分析冰雹的环境场特点。结果表明:(1)伊犁地区冰雹日数时空分布差异较大,随着海拔高度的增加,冰雹日数也迅速增加;年冰雹日数总体呈下降趋势,其线性倾向率为-0.413次·a^(-1);降雹季节性显著,最早发生在3月,最晚在11月初,5-7月是冰雹的高发期,日降雹主要集中在16-20时;冰雹日数从1981年开始减少,突变点出现在1999年,之后冰雹日数显著减少。(2)大多数过程T-ln P图温湿廓线表现为干绝热型,即整层湿度较小,温度露点差>5℃,并总结出各月冰雹发生前关键环境参数阈值。

By using linear regression analysis and Mann-Kendall test,this study statistically analyzed the climatic characteristics of hail days in 10 national stations in Ili region from 1961 to 2018,and the characteristics of the environmental field of the hail were analyzed based on the sounding data of Yining station from 2000 to 2018.The results showed that:(1)There was a big difference in the spatial and temporal distribution of hail days in Ili area,and as the altitude increased,the number of hail days also increased rapidly.The annual number of hail days showed a downward trend in general,with a linear tendency rate of-0.413 time·a^(-1).The seasonality of hail was remarkable.The earliest hail of the year occurred in March,and the latest was at the beginning of November.From May to July,it was the period of the high occurrence of hail,the daily hail was mainly concentrated at 16:00-20:00.According to result of the Mann-Kendall test method,the number of hail days began to decreased in1981,and the turning point appeared in 1999,after which the number of hail days decreased significantly.(2)The temperature and humidity profile of most of the process T-ln P diagrams were of dry adiabatic type,that was,the entire layer had low humidity and the dew-point deficit was greater than 5℃.Meanwhile,the thresholds of key environmental parameters before hail occurred in each month were summarized.